00288nam a2200097Ia 4500008004100000082002800041100001100069245007800080260002400158300000800182140113s9999    xx            000 0 und d  a634.16/018 (082.2)   L1  aUNESCO  aProductivity of forest ecosystems :Proceedings of the Bruselils symposium  a1971bUNESCOcParis  a707